Tinea corporis: causes, symptoms, diagnosis, and treatment

Tinea corporis is a superficial fungal infection on smooth skin other than the scalp, hair, palms, soles, and nails, caused by dermatophytes.


Causes

Tinea corporis is mainly caused by trichophyton rubrum, trichophyton mentagrophytes, trichophyton schoenleinii, trichophyton violaceum, epidermophytom floccosum, microsporum ferrugineum, microsporum gypseum, and microsporum canis. The disease can result from direct or indirect contact with contaminated bathtub or bath towels, and can also be transmitted from tinea manuum, tinea pedis, tinea cruris, onychomycosis, or tinea capitis. Individuals with diabetes or wasting diseases are more susceptible to this disease.


Signs and Symptoms

After pathogens invade the stratum corneum of human epidermis, mild inflammatory reactions result in erythema, papules, and vesicles, followed by desquamation, and skin lesions are often annular. Skin lesions are initially scattered, and can fuse with each other after extending. Sometimes, skin lesions extend to the whole body, especially in patients with immunodeficiency disease or the use of immunosuppressive agents, glucocorticoids, or antitumor drugs. Under the action of the body's defense, the center of the annular lesions can be healing spontaneously with desquamation. The edges composed of active erythema, papules, vesicles, or scales are raised, and the center is flat and with desquamation or pigmentation. Tinea corporis in children can be multi-annular.

Figure 1 typical tinea corporis

Figure 2 generalized tinea corporis

Figure 3 multi-annular tinea corporis in children

Tinea corporis caused by trichophyton rubrum is often prone to spread, more common in the waist, abdomen, arms, and trunk, and is often accompanied by pruritus. Tinea corporis caused by trichophyton mentagrophytes often occurs on the face and lower legs, and is annular or irregular, with significant inflammation. Scratches can cause pustules or deep lesions, and annular, raised indurations can occur locally. Sometimes, epidermophytom floccosum can cause tinea corporis. Microsporum ferrugineum, microsporum gypseum, and microsporum canis can cause tinea corporis, which occurs predominantly in the forehead, cheeks, neck, upper limbs, and trunk, and the skin lesions are often annular or multi-annular. Skin lesions caused by microsporum gypseum and microsporum canis are scattered and flushing, with obvious inflammation. Skin lesions caused by trichophyton violaceum are initially light red papules, macules, or papulovesicles, extending irregularly.


Histopathology

Hyperkeratosis, parakeratosis, acanthosis, edema of the dermal papilla, perivascular cellular infiltration, and flattened epidermal ridges may be observed. Sometimes, vesiculation below the stratum corneum or in the epidermis can be visible. Fungal hyphae in the stratum corneum can be found in periodic acid-Schiff (PAS) stain.


Diagnosis

Tinea corporis can be diagnosed on the basis of typical clinical manifestations, positive fungal microscopy, or dermatophytes isolated from culture.


Treatment

Topical treatment

Common topical medications are imidazoles and allylamines.

Imidazoles include miconazole, econazole, bifonazole, ketoconazole, clotrimazole, sulconazole, sertaconazole, and luliconazole.

Allylamines include terbinafine, butenafine, and naftifine.

Other medications include amorolfine, liranaftate, and ciclopirox.

Systemic treatment

If poor topical treatment, generalized skin lesions, or relapses are present, systemic antifungals may be required.

Most common systemic antifungals are terbinafine and itraconazole.